Processing of image

1. An image processor which is configured:

to receive a signal,

to compare an individual frame under process, included in the received signal, with a preceding processed frame,

to detect changes by dividing pixels of the individual frame into movement blocks of a predetermined size and to detect a given movement block as changed if in said movement block there are at least one pixel whose characteristic value has changed as compared with a corresponding pixel of the preceding processed frame by a predetermined threshold,

to provide an indication of the movement blocks that are unchanged as compared with the preceding processed frame, and

to generate a signal which indicates the changes by including in said signal the information on movement blocks detected as changed and information on movement blocks detected as unchanged such that said signal includes all the movement blocks of the frame under process, wherein the image processor is configured

to provide indication of the movement blocks that are unchanged by copying the pixel values in the movement blocks that are detected to be unchanged from the preceding processed frame.

2. The image processor of claim 1 , wherein the image processor is configured to divide only a portion of the pixels of an individual frame into movement blocks.

3. The image processor of claim 1 , wherein a given movement block is detected as changed if there is at least a given number of pixels whose characteristic value change exceeds a predetermined threshold.

4. The image processor of claim 1 , wherein the characteristic value is a colour value corresponding to one of RGB, YUV, CMYK, B/W and Y.

5. The image processor of claim 1 , wherein the characteristic value is one of a colour value or a signal other than the colour value.

6. The image processor according to claim 1 , wherein the detection of whether the movement block is changed or unchanged is based upon at least one of sum/mean differences, sum/mean absolute differences, variance/standard deviation of differences, and variance/standard deviation of absolute differences.

7. The image processor according to claim 1 , wherein if the processor detects a given movement block as changed on the basis of a characteristic value check of pixels in the movement block, the processor is configured to record also all the movement blocks surrounding the given movement block as having changed.

8. The image processor according to claim 1 , wherein the processor is configured to analyze a change in characteristic values such that if the absolute value of a change in a first characteristic value of a single pixel exceeds said predetermined threshold, the processor finds the characteristic values of said pixel changed.

9. The image processor according to claim 1 , wherein the processor is configured to modify said preceding processed frame by copying to it, from the frame under process, the pixels of the movement block detected as changed and to use said frame changed in this manner also in the comparison which the processor will perform on a frame subsequent to the frame under process.

10. The image processor according to claim 1 , wherein the processor is configured to feed the generated signal to an image coder operatively coupled to the processor.

11. The image processor according to claim 1 , wherein the received signal is a video signal generated by at least one of a camera, video camera, scanner, screen, file or other image source.

12. A method for processing a signal, the method comprising:

receiving a signal,

comparing a single frame included in the signal and being processed with a preceding processed frame,

detecting changes by dividing pixels in the single frame into movement blocks of a predetermined size and by detecting a given movement block as changed, if the number of pixels whose characteristic value changes as compared with the corresponding pixels in the preceding processed frame exceeds a predetermined threshold,

providing an indication of the movement blocks that are unchanged, as compared with the preceding processed frame, and

generating a signal that indicates the changes by including in the signal the information on the movement blocks detected as changed as well as the information regarding the unchanged movement blocks, such that said signal includes all the movement blocks of the frame under process, wherein in said method an indication of the movement blocks that are unchanged is provided by copying the pixel values in the movement blocks that are detected to be unchanged from the preceding processed frame.

13. The method of claim 12 , wherein the movement block is a rectangle.

14. The method according to claim 12 , wherein the method analyzes changes in characteristic values by analyzing changes in colour values and the colour values of a single pixel are detected as changed if the absolute value of a first colour value of the pixel exceeds said predetermined threshold.

15. The method according to claim 12 , wherein the colour values correspond to at least one of RGB, YUV, CMYK, B/W and Y values.

16. The method according to claim 12 , wherein the method modifies said preceding processed frame by copying to it from the frame under process the pixels of the changed movement blocks and uses the preceding processed frame modified in this manner for the comparison to be performed on a frame subsequent to the frame under process.

17. Software for controlling a programmable device for implementing the method according to claim 12 .